Q1. What is photosynthesis?

Ans: The process by which green plants and some other organisms use sunlight to create nutrients from CO₂ and H₂O. Photosynthesis requires the green pigment called chlorophyll and gives out oxygen as a by-product. Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy.

 

Q2. What is starch?

Ans: starch is the most complex carbohydrate compound. It is a biodegradable product. It is a polysaccharide (a carbohydrate e.g. starch, cellulose whose molecules consist of a number of sugar molecules bonded together.) and glucoside (chemical compound) reserve of plants. 

STARCH TEST

The iodine-starch test is a chemical test that is used to test the presence of starch in a leaf (mainly) or an object.

Materials required:

1.        Water

2.        C2H5OH (alcohol/ethanol)

3.        Spirit lamp

4.        Testing tube

5.        Flask

6.        Dropper

7.        Iodine solution

The steps involved to do a Starch test are:

1.        Take a leaf which is exposed to sunlight and is given all the favourable conditions which are necessary for photosynthesis.

2.        Boil it in water, in a flask to soften it. (heat the water from spirit lamp)

3.        Take a testing tube filled with ethanol. Put the soften leaf in the testing tube. Also take a flask which is being heated up by the spirit lamp, put the testing tube in the flask filed with water. Due to this the ethanol will heat up and bleach the leaf. The chlorophyll will be no more in the leaf.

4.        Wash the leaf in normal water to remove ethanol.

5.        Then put the leaf on a white tile and put few drops of iodine solution on the leaf. If the leaf tuns blue-black, starch is present in the leaf.

So, this is how we do starch test.

By Parth Lahoti